Work of cutting an existing water pipe (an example of a fluid pipe) without stopping the water and changing the flow path or installing a valve device at the cut section is conventionally known. The cutting work here includes drilling or making a hole in the outer circumferential surface of the water pipe, and cutting off the water pipe in the pipe axis direction, i.e., making a full cut. The latter is disclosed in Patent Documents 1 to 5, for example.
It is preferable in such work to cover the end face that is exposed by the cutting to prevent corrosion. In the case with a full cut, it is desirable to provide an anti-corrosion treatment to each of the resultant pair of cut faces of the pipe. This is because exposed cut faces of the pipe will allow generation and entrance of rust in the pipe or penetration of water into the boundary between the inner face of the water pipe and the lining layer thereon, leading to inconveniences.
Patent Documents 1 and 2 disclose a method of preventing corrosion by placing a ring-like sealing member on the pair of cut faces formed by making a full cut of a pipe. This method, however, requires considerably complex devices and processes and can be regarded as impractical method in most cases from the viewpoints of economic efficiency and workability.
Patent Document 6 describes a corrosion prevention apparatus having a telescopic double tubular member. With this apparatus, a core member is inserted into an anti-corrosion member in the form of a C-shaped tube, thereby to enlarge the anti-corrosion member in diameter to be pressed against the pair of cut faces of the pipe. Sometimes, however, the anti-corrosion member was installed at a slant when the double tubular member was placed between the pair of cut faces of the pipe, or the anti-corrosion member was displaced from the pair of cut faces of the pipe because of the load applied when the core member was inserted, or the anti-corrosion member was enlarged in diameter unevenly when the core member was inserted. There was thus a scope of further improvement for providing a correct anti-corrosion treatment.